Rigid protective helmet



FIG. 1 is a front right prospective view showing my new design for a rigid protective helmet.

FIG. 2 is a front elevation view.

FIG. 3 is a left side elevation view.

FIG. 4 is a right side elevation view.

FIG. 5 is a rear elevation view; and,

FIG. 6 is a top view. 

The ornamental design for a rigid protective helmet, as shown and described. 